A high power home-made phosphosilicate fiber cascaded Raman laser pumped by 20 W/1.06μm Yb-doped double-clad fiber laser is reported. The effect of reflectivity of output couplers on the laser threshold and efficiency are investigated experimentally. The laser threshold decreases with increasing the reflectivity of output FBG. The maximum continuous-wave output power of 2.8 W is obtained by 25.7% output coupler while the launched pump power is 12.1 W. The corresponding slope efficiency and the conversion efficiency are about 31.3% and 23.1%, respectively. At the maximum output power, the power fluctuation at 1.48 μm in two hour is observed to be less than 5%.